One system to control an engine during a condition of valve actuator failure is described in U.S. Pat. No. 6,278,932. The system description presents a way to deactivate a bank of cylinders in response to a valve actuator failure. In addition, an actuator controller is provided for each bank of the engine and each controller is configured to operate valves, fuel injection, and ignition if communication between the actuator controller and engine controller is disrupted.
The above-mentioned method can also have a disadvantage. For example, the system uses a single CAN data bus to communicate between the valve controllers and the engine controller. This configuration may be adequate during some conditions but may be inadequate during others; such as, when a valve is degraded. Generally, control and status commands for each cylinder are sent between the valve controller and the engine controller. The commands and status may be updated as often as each cylinder event. If a valve stays open or does not open, it may be desirable to inhibit spark in a cylinder while the valve is not operating as desired. During these conditions, it may be desirable to inhibit spark within as little as forty crankshaft angle degrees after a valve has not closed, for example. However, if a request to inhibit a spark event is transmitted from a valve controller to an engine controller at higher engine speeds, then there is less time to communicate between cylinder events. Consequently, the amount of time available to transmit data between the valve controller and the engine controller decreases as engine speed increases. This can increase the possibility of late or undeliverable data. As a result, it may be possible for a combustion event to occur in a cylinder when an intake or exhaust valve is open.
The inventors herein have recognized the above-mentioned disadvantage and have developed a system that improves communication and data exchange between a valve controller and an engine controller.